Response of lateral placement depths of subsurface drip irrigation on okra (Abelmoschus esculentus)

Subsurface drip irrigation is defined as application of water below the soil surface through emitters, with discharge rates generally in the same range as surface drip irrigation. It has many advantages over surface drip. To see the response of subsurface drip irrigation on okra yield, a study was conducted at Indian Agricultural Research Institute, New Delhi, India during 2003 and 2004. Okra (Abelmoschus esculentus) crop was cultivated in three sub-plots with four treatments of drip lateral depths viz. on the surface, and at depths of 0.05, 0.10 and 0.15 m below the soil surface. Laterals used for three sub-plots were inline drip laterals having discharge rate of 2.03  10-6, 1.53  10-6 and 1.22  10-6 m3 s-1 per meter length. Crop was irrigated as per irrigation schedule to fulfill its water requirement. The observations were recorded on growth parameter, soil moisture content and yield of crop. The study indicated that soil moisture content under subsurface drip irrigation was more uniform as compared with surface drip. It was found that plant height, yield and water use efficiency of okra increased due to subsurface placement of laterals. The maximum increased okra yield was found to be 5.22, 13.48 and 11.56 % under 0.05, 0.10 and 0.15 m depths of lateral placement, respectively, as compared to that under surface drip. On the basis of the study, it was recommended that laterals of subsurface drip irrigation should be placed between 0.10 to 0.15 m depths below soil surface for higher okra yield.